lis 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[April, 



down the shaft, because the pressure of the atmospliere above is gt'eafer. 

 When the baromeler is rising, the men are comparatively safe, because the 

 enemy is retreating frum them ; but when it falls, all this explosive matter 

 comes forth into the mine from the goaf. Then, of course, when the baro- 

 meler falls, there is an overflow, or rather, an underflow of ^as from the goaf 

 into the workings of the mine, making it explosive. Even the men themselves 

 do not know anything of this fact. I will make an experiment to show you 

 how this acts by taking a porous substance, and exhausting the atmosphere 

 from it. I am using only a piece of charcoal, which is a bad thing, because 

 it is by no means sufficiently porous. If I increase the pressure of the atmo- 

 sphere, I expect you will soon see the (;as, or fire-damp, creeping out of the 

 cavities of the charcoal. You will now perceive it rushing cut of all these 

 cavities, even with a very moderate diminution of pressure of the atmosphere, 

 and imder very unfavourable circumstances as compared with the enormous 

 cavities in the mine. You see it does not it come out and overflow. (The 

 lecturer showed this by suspending the charcoal in water under the receiver 

 of an air-pumpj Once in a thousand days, or any other time, a permJ would 

 come round in which this space would serve as a receptacle for fire-damp, 

 being full of the explosive mixture which comes forth when the barometer 

 falls. When these ninety-five men were killed, it was actually by the draw- 

 ing of a jud ; it was at the very edge of the jud. It was in a mine well ven- 

 tilated, and free from gas as mines go. The underviewer actually declared 

 that he never saw any gas in it in his life. Tlie gas, however was found by 

 others. They were drawing that jud at the time of the accident; whether 

 the jud or stones had broken the Davy lamp, and so set fire to the gas, we 

 cannot tell. We saw some lamps at the very place; but yet we cannot tell 

 accurately how it occurred. All we know is that they were enlarging the 

 cdjie of the goaf in that part when the accident took place. Another ex- 

 plosion took place. Some of the men were choked ; others were choked and 

 burnt ; but they were all killeil by suff'ocation, so that there were two causes. 



Without saying whether this was or was not the cause, we venture to think 

 that the ventilation of the goaf should be attended to by itself, apart from 

 the rest of the mine. We were not fitting judges of the fact as to \vhether 

 the mine was or was not sufficiently ventilated ; those who are qualified to 

 give an opinion on the matter say that it was. But as regards the goaf, we 

 venture to say that was not ventilated enough : it was avery feeble current of 

 air, not carried forward to the extent to which it ought to have been in a 

 mine, where there is a liability to the action of fire-damp. The safety of the 

 miners hangs upon a change in the baromeler, a sudden increase of gas in 

 the mine, and various other circumstances. 



M'ishing to make our examination as quietly as possible, and to have our 

 Report as complete as we could, we proposed upon general principles the 

 following plan for the prevention of these sad calamities. That a pipe should 

 be laid from the goaf into the upcast shaft, or into what is called the return 

 way, and cither by a draft, or some mechanical means, to draw oS' the air 

 from the goaf. That the pipe shall be thrust up into the goaf, then carried 

 to the upcast shaft, and exhausted by machinery. Now my notion was with- 

 out any mechanical means, merely by the draft of the upcast shaft, if con- 

 nected with the goaf, that such an arrangement would be sufficient to venti- 

 late the goaf. I am going to shew you that that draft is sufficient to venti- 

 late the goaf. Here is a pipe entering the chimney ; I have carried off this 

 pipe a certain distance ; part of it is made of glass, another portion of water- 

 proof cloth carried out at the further end, at which place there is such a 

 draft that a candle can hardly be kept lighted there. It is just that kind of 

 draft which I propose to use in the removal of the gas from the goaf. That 

 is what We call the return way, and this the upcast shaft : not that I mean 

 to say that the return in the mine is all air, because such isnot the case. Our 

 proposition is to have in such return way a pipe laid down purposely to pro- 

 ceed to the goaf. But I must show how it is such a small fire creates so great 

 a draft. The velocity of the air in the mine is measured by smoke from the 

 explosion of a little gunpowder ; and I will imitate their process for the same 

 purpose; the draft which I liave here, being of course very small, compared 

 with that which exists in the mine, although about in the same proportion to 

 theirs. They have two fires in the upcast; and they informed me that there 

 was half-a-ton of coals on each. These fires are always kept up, so that 

 there is continually a ton of coals in combustion in them. You may imagine 

 from that fact, how great the draft must be. A little gunpowder will now be 

 fired at the other end, which will enable you to judge of the velocity of the 

 draft. (This was done, and the passage of the smoke through tlie pipe could 

 he seen through the glass.) You now perceive the beautiful manner in which 

 the smoke passes from end to end. Now it is here ; then it is at the middle 

 of the pipe ; and now again it is gone out at the end. This will give an idea 

 of the application of this plan, and will show how a draft of this kind could 

 draw the gas out. Were 1 to give an account of the number of cubical feet 

 drawn out in one hour, you would be perfectly astonished. I will now show 

 how sound these principles are in theory, I cannot at present see any diflS- 

 culty in practice. Here is a mere register hole going into a flue. The regis- 

 ter hole .is applicable in principle and also in practice, (The lecturer showed 



how the model goaf could be cleared of gas by a pipe passing up into it, the 

 other end of the pipe entering a flue of a fire-place, representing, for the 

 time being, the upcast shafi, which clearly proved that no gas could remain 

 at a lower point in the goaf than the end of the pipe introduced into the 

 goaf) The principle cannot fail to answer. It merely requires a pipe of any 

 sort carried into a place, with a reasonable draft in it. Draft, of course, is 

 absolutely necessary. There is an oljjection which occurred to myself, and I 

 dare say to both of us, and most likely also to the coal-owners. Indeed the 

 papers, with that infallibility which belongs to ihem, have at once declared 

 that our plan w ould do no good ; that every coal-owner, without exception, 

 was satisfied that it would not answer. The difficulty which I allude to is 

 this ; there is in a mine what they call the oreep. When a mine is in work, 

 and the pillars exist, these ways creep. Our proposition is to lay down iron 

 pipes which will reach to the upshaft, or return way, by a flexible extremity : 

 but then there is the creep. That is to say, when the pillars are still standing 

 the superincumbent weight of the earth would squeeze them bodily into the 

 ground ; the earth would ooze in, and this they call creeping. The whole 

 earth is like a little bit of sealing-wax with a candle brought together in this 

 sort of way. Of course, that would destroy any arrangement, as to anything 

 let in the earth, like the water or gas-pipe of London. I have since proposed 

 a pipe hung up in the air; but, I believe, that a pipe of that sort, a flexible 

 air pipe would do, and you might have access to it at any time. I think it 

 possible that they might block up one of these ways in the pit, and keep the 

 pipe safe from failure or harm. Upon the plan of the Haswell mine there 

 would be no difficulty at all in conveying such a pipe from the goaf. lean- 

 not tell w hat the plans in other mines are, but I am satisfied that 50/. would 

 lay down a very good pipe from the return to the goaf. At least, that is my 

 conviction: I am perfectly sure that the principle is correct, although the 

 practice may show difficulties ; but still, I think, not such as are insurmount- 

 able. I was observing that the pipe might be temporary, but I might say, it 

 docs not need that ; the pipe might go in. There is an objection made to this, 

 that they cannot form their goafs entirely at will. We do not want to do 

 so. If a pipe of that sort went about six feet up into a goaf, no variation of 

 the atmosphere would ever bring the fire-damp into the mine. Well, then, 

 having got six feet into the goaf, they may go on 30, 40, or 50 feet, in tlie 

 further working of the mine, before they need change the position of that 

 pipe, or before the outer extremity would be below the highest point of the 

 edge of the goaf. We are not bound to find with mathematical exactness the 

 highest elevation in the goaf; all we have to do is, to keep the pipe within 

 the part where the fire-damp is, which would be an easy thing to do. M'e 

 have no idea that this process can be anything so perfectly mathematical, or 

 that if it intermits for an hour, it can do harm. My notion is this, that if it 

 work one day in three, it would keep the mine perfectly safe by removing 

 the flre-damp entirely out of the way. That is my impression ; whether it 

 will prove so or not, I cannot at all say ; that must depend a good deal on the 

 circumstances of each mine individually. The great point with us is to 

 draw the air away. I have said already, that one of fire-damp will render 

 fourteen of air explosive. The general process of ventilation is, to drive air 

 into a mine and goaf, mixing it altogether, and thus making an explosive 

 mixture. We should ventilate the goaf by drawing off the fire-damp, and 

 therefore I prefer this principle of drawing out its contents to sending air into 

 It. We do not want to carry fresh air into the goaf; we would rather keep 

 the poison out of the system, than send in a great flood of water to drive it 

 out afterwards. The thing is, to prevent the evil ; and if you take away one 

 measure of gas, you prevent the chance of fifteen explosions afterwards ; 

 w hereas, throw in one measure of air into the goaf, and you throw out a mea- 

 sure of gas, which will make fifteen measures of explosive mixture. Every- 

 thing, therefore, points to the withdrawal of the gas rather than the throwing 

 in of the air. 



This principle of withdrawing gas, I am glad to find, is not new among the 

 coal-owners. Mr. Ryan's method of ventilating mines is one which essen- 

 tially depends upon draw ing or draining off' the gas from the mine. To my 

 mind his principle seems very beautiful, aud cannot but be most valuable 

 in very many cases, although in some it is said to have failed. 1 know that 

 aSman may fail twenty times in a good thing, and yet succeed in nume- 

 rous instances afterwards. 



There was another gentleman, of the name of Taylor, who proposed, many 

 years ago, to ventilate mines by drawing out gas from the mine by a parti- 

 cular apparatus. Our proposition has been limited entirely to the goaf ; by 

 going to that part which is not ventilated by the common means. It is in the 

 goaf that we would lay this drainage. AVedo not venture so far as to sayj 

 it would certainly succeed in practice in the mine; but it does seem to us, 

 that a cavity like this should have some attention paid to it for the removal 

 of the fire-damp from it. 



